Enlarging the Brunch Jacket from size 8 to size 10/12

My DGD wears a size 12 (I think). I’ve taken her measurements and the’re all over the map, but definitely larger than a size 8. She’s nine years old, thin and tall. Her measurements are chest: 26”, waist: 22.75”, hips: 29” and BW: 13”. She is 56” tall. Her arm length is 19”! In other words, she is all arms and legs! If anyone can give me some guidance on how much and where to add for her, I’d be very grateful. Obviously, I’ll have to start by adding length; that’s not the main problem. The main issue is where to add width. I’m thinking she will need extra in the armhole length, maybe 3/8” as well as in the back length, extra width in the sleeve, a larger neckline (and facing), etc. TIA.

You know what I would do?
I’d use the Building Block Dress block to get the right chest, shoulder, armhole width… That goes up to size 12. Make a basic dress or two to be sure of the fit.
Then I’d take the elements of the Sunday Brunch: wide cross over front placket, short bodice with gathered skirt, Mandarin collar and wide sleeves and draft them into the block that now fits.
You reference back to the Sunday Brunch to get a feel for how it all comes together, but the fitting all comes from the appropriately sized building block dress pattern.
Sounds like a great project.

Thanks for your suggestion, Lightening. I must say, starting from scratch sounds a little daunting. I do have the Sunday Brunch Jacket pattern and I would feel more comfortable starting there. I’m not ready to start drafting my own patterns yet, although I do appreciate the suggestion. I feel the changes, except for length, are going to be under 1” in width in each case so that sticking to the original pattern makes more sense for me. I only wish Liesl had made it available up to size 12. (Whine, whine 😉).

Based on your granddaughter’s measurements, I’m wondering if you really need to increase the width at all. Her chest measurement, which is the most important measurement for a jacket, is within the size 8 measurements, and her height corresponds with a 10, only one size bigger. If there was more of a disparity between height and chest sizes you might want to grade up for shoulder and armpit ease, but in this case, I think you would probably be fine with just lengthening the jacket. I haven’t made this pattern, though, so maybe someone else who has can chime in with what they thought about the shoulder and armpit ease in the size 8.

I didn’t look at the sizing, but since Maggie’s been helpful and done so, then yes, just make the size 8 and add length.
I think your daughter and my son must be the same shape. He’s nine and I generally make a size 8, lengthened to 10-12 then throw on an extra 2 or 3″ sleeve length again!
Lengthening will be easy as the sleeves are quite straight from memory; you may be able to add it all at the cuff end.
Remember to lengthen the bodice proportionally to the skirt to keep the nice balance. I imagine it would be about 1/5th bodice and 4/5ths skirt, (or maybe closer to 0.25:0.75, do measure it won’t you) so if you were adding 5″ for example, you’d add 1″ to the bodice and 4″ to the skirt.
This pattern isn’t sized to go on over bulky sweaters like the School Days Coat, but if the chest measurement is right then the sizing should be fine.
Easy!

Mmmmm. Maybe I’m trying to make it too hard for myself. I was thinking that I’d have to lengthen the armhole and the sleeve head by 1/4” – 1/2” to make enough room for her long torso. I may make up a quick and dirty muslin of just the bodice – no sleeves – before I make up the real thing. I know it sounds like a lot of work for a child’s jacket but I want it to be comfortable, and her to like wearing it so that it’s something special, not something she’s forced to wear to please me.
I won’t forget about the proportions, Lightening, and will measure before I lengthen.
Thank you to both you and Maggie for your very helpful replies. I think I have a good idea what I’m doing now, whereas before I was bumbling around in the dark. These are great patterns and the discussion support is amazing! I will let you know how it turns out.

Do you have a jacket that fits the way you/she likes? I suggest measuring that to compare. Keep in mind that a jacket goes over other sleeves, so more room in the armholes is better. Maybe add 1/2 inch in length a few inches down from the shoulder in the bodice, and the sleeve cap to match.

Thanks for the suggestion, Reeni. This is supposed to be a surprise for her and my DD is clueless about sewing (by choice). I might manage to borrow and measure a well fitting jacket, but we’re not there that often, and it would definitely not be able to do it secretly. As to asking my DD to do it, she’s so allergic to tape measures, she balked at measuring my DGD! I’ll think about it.

Nicole, please forgive me not thanking you sooner for all your helpful suggestions. My ninety-year-old mother gave us a scare last week, necessitating a stay in the hospital. Thankfully, she’s well again, or at least we’ll enough to come home, but everything else went by the wayside. Sewing has been put on hold for now, unfortunately, but I’m very grateful for your help and very much appreciate your insight.

Nicole, please don’t concern yourself in the circumstances. I’m sorry to hear of your loss. I can’t believe it’s been a month since I first posted. My mom had a relapse and has still not recovered. My sewing seems destined to be put on prolonged hold, at least for another month or two. I’d like to thank everyone for their generous suggestions. Nicole, yours were particularly helpful. My DGD wears glasses, too.